Adjustable motorized screen mount

ABSTRACT

The invention relates to an adjustable motorized screen mount comprising a stand ( 12 ), adapted to be placed on a floor or attached to a wall or a ceiling; a bracket ( 14 ), adapted to be attached to a screen; and a motor, arranged to rotate a motor output shaft such that, upon rotation of the motor shaft, the rotary motion is transmitted, via a mechanical transmission comprising a multi-stage hypocycloid reduction geat train, to a transmission output shaft which moves the bracket ( 14 ) relative to the stand  912 ).

FIELD OF THE INVENTION

The present invention relates to an adjustable motorized screen mountcomprising a stand, adapted to be placed on a floor or attached to awall or a ceiling; a bracket, adapted to be attached to a screen; and amotor, arranged to rotate a motor output shaft such that, upon rotationof the motor shaft, the rotary motion is transmitted, via a mechanicaltransmission, to a transmission output shaft which moves the bracketrelative to the stand.

BACKGROUND OF THE INVENTION

For having the best viewing comfort when watching the screen of atelevision set, a video monitor, a computer monitor or the like, asuitable viewing angle should be selected, i.e. the screen and theviewer should be positioned in such a relation to each other that theperceived watching experience of the viewer be optimized. For a viewerto be able to watch the screen from different locations at differentoccasions, it is desirable to be able to turn the screen for an optimumviewing experience from each location.

Also the ability to move the screen is desired. For example, using amount that can translate a screen vertically, it is possible to hidee.g. a flat panel TV behind any piece of furniture, and to elevate itonly when it is to be used.

Adjustable screen mounts are known; for example, WO2004111523 disclosesan adjustable screen mount for mounting a screen on a wall, wherein themount enables the screen to be turned about a vertical axis. Alsomotorized adjustable screen mounts are known; e.g. European RegisteredCommunity Design no. 000503420-0001, referred to below as the Lava mountas the device is sold by Lava Electronics, discloses a motorized mounthaving a wall mount bracket and a screen mount bracket that can beturned up to a maximum of 90° in relation to the wall bracket around apivot axis. The wall bracket of the Lava mount further incorporates anactuator, consisting of a motor, which operates a telescopic arm. Oneend of the telescopic arm is journalled in the wall bracket, and theother in the screen bracket. In its retracted position, the actuator ishidden behind the screen, which then is parallel to the wall and spacedfrom the same by a distance that is sufficient to accommodate the entireactuator. By operating the motor at a constant speed, the arm isextended at a constant speed, which makes the screen bracket rotate at adecreasing angular speed around the pivot axis.

The spacing between the wall and the screen in the retracted position,as well as the visual exposure of the actuator as the mount is opened,may be undesired from an aesthetic point of view. Further, as the speedof the rotation of the screen bracket will vary across the turning rangeof the bracket, an operator may find the rotary speed to be either tooslow or too fast depending on the position of the bracket. As a typicalelectric motor operates at a constant, high rotary speed, it isdifficult to achieve a slow and constant motion of the screen bracketwithout using a large or complicated transmission mechanism. It may alsobe desirable to be able to adjust the stand manually, without having tolocate, e.g., a remote control for operating the motor.

Another problem with known adjustable wall mounts, is that they have aturning range that is limited by the construction of the rotarymechanism of the mount. No motorized mount has a mechanism that issuited for turning the screen bracket indefinitely about an axis, aswell as elevating/lowering the screen bracket relative to a stand orwall bracket.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an adjustable,motorized screen mount which is compact, simple in its construction andcomprises few moving parts; which can be adjusted by hand as well as bya motor; which is capable of carrying and moving heavy weights; whichhas the motor and all its transmission parts in hidden in a single,aesthetically appealing casing; whose turning range is not limited bythe rotary mechanism; and which can either be placed on a floor ormounted to a wall or a ceiling.

This object is achieved with an adjustable motorized screen mountcomprising a stand, adapted to be placed on a floor or attached to awall or a ceiling; a bracket, adapted to be attached to a screen; and amotor, arranged to rotate a motor output shaft such that, upon rotationof the motor shaft, the rotary motion is transmitted, via a mechanicaltransmission, to a transmission output shaft which moves the bracketrelative to the stand, wherein the mechanical transmission comprises amulti-stage hypocycloid reduction gear train.

With a multi-stage hypocycloid reduction gear train, it is possible toobtain a sufficient transmission ratio between an electric motor and atransmission output shaft within a compact volume. The shape and rotaryaxis orientation of a hypocycloid gear train makes it well adapted tofit together with the whole transmission, including the motor and anyclutch, inside a single tubular housing that will visually only appearto be a hinge or a support or frame member. This configuration is wellsuited for both rotary and axially translatory motions. At the sametime, a hypocycloid gear with a high transmission ratio has a highnumber of teeth in simultaneous engagement, which makes the devicecapable of reliably carrying and moving heavy weights. Further, ahypocycloid gear train comprises only few moving parts, making itinexpensive and easy to assemble.

Preferably, the multi-stage hypocycloid reduction gear train comprises afirst internal ring gear, connected to the stand, and a second internalring gear, connected to and arranged to, upon rotation, move thebracket, the internal ring gears being coaxial; an orbit gear,eccentrically arranged inside said first and second internal ring gearsand having a first set of teeth meshing with the first internal ringgear and a second set of teeth meshing with the second internal ringgear; and a rocker shaft, connected to the motor output shaft and havingan axis of rotation concentric with said first and second internal ringgears, the rocker shaft having an eccentric body journalled centricallyin said orbit gear.

This configuration of a hypocycloid gear train may be implemented in aparticularly compact volume, using particularly few parts. The wholetransmission of a mount capable of carrying a large plasma screen may beaccommodated in a narrow tube with 50 mm diameter. The height taken upinside the tube of, e.g., a two-stage hypocycloid gear train may be aslow as 30 mm.

In a preferred embodiment, the transmission output shaft is arranged to,upon rotation of the motor, turn the bracket relative to the stand aboutan axis of rotation parallel to, or concentric with the axis of rotationof the transmission output shaft.

This embodiment is particularly well suited for imparting a rotarymotion to a bracket, as the mechanism itself does not inherentlyconstrain the maximum turning range; for example, a mount that is notobstructed by any other objects, such as a floor mount, may be rotated alimitless number of turns, or be provided with end stops where deemedsuitable.

Preferably, the mechanical transmission further comprises a frictionalclutch, and more preferably, the frictional clutch is a spring-loadedtoothed clutch comprising first and second clutch disks having surfacesfacing each other, the surfaces being profiled with crests extendingradially. Thanks to the clutch, it is possible to turn the bracketwithout operating the motor. Further, should any object obstruct thetrajectory of the bracket or screen, or should any force otherwise beunwillingly applied to the screen, a slip of the clutch will prevent anydamage to the transmission or the motor.

In a preferred embodiment, the circumferential surface of thetransmission output shaft is in threaded engagement with the innersurface of a circular cylindrical tube that is connected to the bracket,such that the transmission output shaft is arranged to translate thetube along the rotary axis of the transmission output shaft uponoperation of the motor.

This embodiment is particularly well suited for imparting a translatorymotion to a bracket. Any threaded engagement may be used, i.e. there maybe threads on the circumferential surface of the transmission outputshaft, and any type of structure arranged to mesh with the threads onthe inner surface of the tube. Or, the threads may be present on theinner surface of the tube, or on both surfaces.

Preferably, the multi-stage hypocycloid reduction gear train has a totaltransmission ratio of between 200:1 and 2000:1, as a transmission ratiooutside this transmission range will either make the mount unable tomove the heavy weight that a large screen represents, or yield a motionof the screen that an operator would find to be either too slow or toofast.

Preferably, the multi-stage hypocycloid reduction gear train is atwo-stage hypocycloid reduction gear train, as two stages are sufficientto achieve a high enough transmission ratio, and minimizes the number ofcomponents required in the device.

Preferably, the motor and the hypocycloid gear train are contained in asingle cylindrical housing, as this is an aesthetically very attractiveembodiment of the mount.

In a preferred embodiment, the screen mount is arranged to translate aswell as rotate the bracket relative to the stand.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of an adjustable motorized screen mountaccording to the invention.

FIG. 2 is a sectional view of a transmission for a reconfigurablemotorized screen mount according to the invention.

FIG. 3 is an exploded view, in perspective, of the transmission in FIG.2.

FIG. 4 is an exploded view, in perspective, of the transmission in FIG.2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In FIGS. 1-4, like reference numerals refer to like elements, and forclarity, all reference numerals and/or elements are not shown in allfigures.

FIG. 1 illustrates schematically an exemplary embodiment of anadjustable motorized screen mount 10, which is adapted for mounting ascreen onto a vertical wall or a ceiling. The screen mount 10, which inthe figures is oriented to be mounted vertically on a wall, but might aswell be mounted horizontally to a ceiling, comprises a stand 12 and abracket 14. The stand 12 has a flat surface, which is provided withmounting holes 18 for fixing the stand 12 to the wall by means of screws(not shown). The bracket 14 is provided with mounting holes 19 forfixing a screen (not shown) to the bracket 14 by means of screws (notshown). Further, the bracket 14 is connected to the stand 12 by means ofa “motorized hinge”, i.e. a tubular housing 22 containing a transmissionthat is further described with reference to FIGS. 2-4.

The transmission of FIGS. 2-4 comprises an electric motor 24, atwo-stage hypocycloid reduction gear train 26, and a clutch assembly 28.The housing 22 is attached to the bracket 14 and rotatably journalled toupper and lower hinge support portions 30, 32 (FIG. 1) of the stand 12.

The motor 24 is arranged to rotate a motor output shaft 34, which uponoperation of the motor 24 transmits a rotary motion through thehypocycloid gear train 26 and the clutch assembly 28 to a transmissionoutput shaft 36, which is fixed to the tubular housing 22. In thisexample, the hypocycloid gear train 26 has a transmission ratio ofapproximately 1250:1, i.e. 1250 turns of the motor output shaft 34 wouldroughly result in one complete turn of the clutch assembly 28, andconsequently of the tubular housing 22 as well as of the bracket 14.

The electric motor 24 receives a drive current from a motor controllervia motor drive cabling 40.

A further clarification of the operation and details of the hypocycloidgear train 26 and the clutch assembly 28 will now follow.

Rotary motion of the motor output shaft 34 is transmitted into thehypocycloid gear train 26 via a rocker shaft 42, connected to and havingan axis of rotation concentric with the motor output shaft 34. The lowerend of the rocker shaft 42 is journalled in a lower rocker shaft bearing44 in the centre of a first internal ring gear 46, which is fixed to thelower hinge support portion 32 of the stand 12 via the housing of themotor 24. The first internal ring gear is, in this example, providedwith 52 teeth facing radially inwards. In its upper end, the rockershaft 42 is journalled in an upper rocker shaft bearing 45 in the centreof a second internal ring gear 48. The second internal ring gear 48,having 53 teeth, is centrically journalled in a ring gear bearing 49that is located in an upper portion of the first internal ring gear 46.Further, the rocker shaft 42 has an eccentric body 51, which isjournalled centrically in lower and upper orbit gear bearings 53, 55 inan orbit gear 70. The orbit gear 70 is eccentrically arranged inside thefirst and second internal ring gears 46, 48, and has a first set of 50teeth 72 and second set of 51 teeth 74 around its perimeter. The firstand second sets of teeth 72, 74 of the orbit gear 70 mesh with the teethof the first and second internal ring gears 46, 48, respectively. Theorbit gear 70 is thus arranged to orbit inside the ring gears 46, 48.

In the first reduction stage of the two-stage hypocycloid gear train 26,a complete turn of the motor shaft 34 will result in the orbit gear 70rolling a complete turn on the internal teeth of the first internal ringgear 46. At the end of this turn, the orbit gear 70 will have rotated 2teeth or 2/50 revolutions, i.e. the first reduction stage of thehypocycloid gear train 26 has a transmission ratio of about 25:1.

In the second reduction stage of the two-stage hypocycloid gear train26, a complete turn of the orbit gear 70 around its axis, while it'srolling along the internal teeth of the second internal gear 48, willresult in a rotation of the second internal ring gear 48 of one tooth.The second reduction stage thus has a transmission ratio of about 50:1,resulting in a total transmission ratio of the complete two-stagehypocycloid gear train 26 of about 1250:1.

The second internal ring gear 48 is connected to a toothed,spring-loaded clutch assembly 28, comprising a first clutch disk 56,which is attached to the second ring gear 48, and a second clutch disk58, which is connected to the transmission output shaft 36 via splines60 that are parallel to the axis of rotation. The clutch disks' 56, 58surfaces facing each other have identical triangular profiles withcrests extending radially, so as to provide increased friction to arotary sliding motion of the clutch disks 56, 58 relative to each other.In order to provide an adjustable friction of the clutch 28, e.g. foraccommodating for different screen weights when attaching the mount 10horizontally to a ceiling, the clutch 28 is provided with a frictionadjustment spring 62. Any clutch friction within a designed range may beobtained by translating a pressure plate 64 upwards or downwards bymeans of a screw (not shown) that penetrates a hole in the upper surfaceof the transmission output shaft 36, and engages with threads in a holein the pressure plate 64.

The transmission output shaft 36 is force fit to the tubular housing 22,such that a rotary motion of the motor output shaft 34 will translatethrough the two-stage hypocycloid gear train 26 and the clutch assembly28, via the transmission output shaft 36 and the tubular housing 22, tothe screen bracket 14, which will turn about the rotary axis of themotor output shaft 34. And thanks to the clutch assembly 28, a manualrotation of the screen bracket 14, willingly or unwillingly, or anunexpected stop due to any object obstructing the screen's trajectory,will not cause any damage to the transmission or the motor 24. In analternative embodiment void of a clutch assembly, the second internalring gear 48 itself may, in fact, also constitute the transmissionoutput shaft.

Even though the mechanism itself does not limit the rotation of thebracket, it may be desired to have the ability to pre-set particularpositions. For instance, in a “TV Off” position of an embodiment of theinvention adapted for mounting a TV onto a wall, the TV may be retractedto the wall, and the bracket may be set to automatically swivel out to adefault “TV On” position when the TV is switched on. User definedpositions, e.g. a “Couch” or a “Kitchen” position, may also be set.

As it is possible to operate the mount by hand, it is not sufficient tokeep track of the position of the bracket by counting the number ofrevolutions of the electric motor. Instead, the mount is provided withthree magnetic sensors on the lower hinge support, located at threedifferent radial distances from the axis of rotation of the tubularhousing. Each sensor is arranged to interact with a magnet, each ofwhich is located on a washer having a diameter adapted to the radiallocation of the corresponding magnetic sensor. The three washers areconcentric, individually adjustable around the rotary axis of thetubular housing, and arranged to rotate with the tubular housing. Inthis manner, three adjustable and detectable setpoint positions of themount are obtained.

Using the mechanism above, it is also possible to obtain axial, withrespect to the rotary axis of the motor, translation of the bracketrelative to the stand. By locking the tubular housing to the stand withrespect to rotation and instead allowing it to be moved in the axialdirection, a rotary motion of the transmission output shaft may, usingthreads on the outer circumference of the transmission output shaftmeshing with threads on the inner surface of the tubular housing, betranslated to an extensive or retractive motion of the tubular housing.

It should also be within the abilities of a skilled person to connect arotary “motorized hinge” in series with an axially translativemechanism, in the same or separate housings, to achieve rotary as wellas translative adjustment capabilities in one single motorized screenmount.

The embodiments described in detail above are adapted for mounting on awall or a ceiling. Any person skilled in the art is capable of adaptingthe screen mount for positioning on a floor, e.g. by modifying the shapeof the stand and the bracket, and by changing the configuration of themount so as to have the tubular housing located centrally behind orbelow the screen.

Further, there are several types of hypocycloid gear trains; in the typedescribed above, it is the inner gear that undergoes an orbiting motion,but the function would be similar if the inner (orbit) gear would bejournalled on a centric bearing and the ring gears would beeccentrically journalled, and undergo the orbital motion, instead. Also,the complete gear train may be turned inside out, i.e. instead of havingan inner (orbit) gear with two sets of teeth connecting two ring gears,it is also possible to use a ring gear, having two sets of teeth in asimilar manner, connecting two inner (orbit) gears.

Any two-stage hypocycloid reduction gear train may be used for a screenmount according to the invention and is within the scope of the appendedclaims. A preferred configuration from a compactness point of view ishowever an eccentrically journalled orbit gear with two sets of teeth,connecting two internal ring gears, along with the general teachings ofthe detailed description of an exemplary embodiment above:

As a skilled person will realize, also any number of stages greater thantwo, in the multi-stage hypocycloid reduction gear train, will alsoenable the construction of compact, high transmission ratio “motorizedhinges” of the type shown, and are within the scope of the appendedclaims. Two stages however yield a sufficient transmission ratio in thiscase and should therefore be regarded as a preferred number from afabrication cost point of view.

The invention is not limited to the specific embodiments describedherein; many variations and modifications will be considered by a personskilled in the art. All those alternatives are within the scope of theappended claims.

1. An adjustable motorized screen mount comprising a stand, adapted tobe placed on a floor or attached to a wall or a ceiling; A bracket,adapted to be attached to a screen; and a motor, arranged to rotate amotor output shaft such that, upon rotation of the motor shaft, therotary motion is transmitted, via a mechanical transmission, to atransmission output shaft which moves to bracket relative to the stand,wherein the mechanical transmission comprises a multi-stage hypocycloidreduction gear train.
 2. A screen mount according to claim 1, whereinthe multi-stage hypocycloid reduction gear train comprises a firstinternal ring gear, connected to the stand, and a second internal ringgear, connected to an arranged to, upon rotation, move the bracket, theinternal ring gears being coaxial; an orbit gear, eccentrically arrangedinside said first and second internal ring gears and having a first setof teeth meshing with the first internal ring gear and a second set ofteeth meshing with the second internal ring gear; and a rocker shaft,connected to the motor output shaft and having an axis of rotationconcentric with said first and second internal ring gears, the rockershaft having an eccentric body journalled centrically in said orbitgear.
 3. A screen mount according to claim 1, wherein the transmissionoutput shaft is arranged to, upon rotation of the motor, turn thebracket relative to the stand about an axis of rotation parallel to theaxis of rotation of the transmission output shaft.
 4. A screen mountaccording to claim 1, wherein the transmission output shaft is arrangedto upon rotation of the motor, turn the bracket relative to the standabout an axis of rotation concentric with the transmission output shaft.5. A screen mount according to claim 3, wherein the mechanicaltransmission further comprises a frictional clutch.
 6. A screen mountaccording to claim 5, wherein the frictional clutch is a spring-loadedtoothed clutch comprising first and second clutch disks having surfacesfacing each other, the surfaces being profiled with crests extendingradially.
 7. A screen mount according claim 1, wherein thecircumferential surface of the transmission output shaft has a threadedengagement with the inner surface of a circular cylindrical tube that isconnected to the bracket, such that the transmission output shaft isarranged to translate the tube along the rotary axis of the transmissionoutput shaft upon operation of the motor.
 8. A screen mount according toclaim 2, wherein the multi-stage hypocycloid reduction gear train has atotal transmission ratio of between 200:1 and 2000:1.
 9. A screen mountaccording to claim 2, wherein the multi-stage hypocycloid reduction geartrain is a two-stage hypocycloid reduction gear train.
 10. A screenmount according claim 1, wherein the motor and the hypocycloid geartrain are contained in a single cylindrical housing.
 11. A screen mountaccording to any of the previous claims, wherein the screen mount (10)is arranged to translate as well as rotate the bracket relative to thestand.